One week before the "Double Twelfth" Shopping Festival, many people are ready to "chop hands" again. Some people focus on the goal of "hoarding" milk. Pasteurized milk, high calcium milk, lactose free milk... At present, there are many kinds of milk sold on the market. Recently, a product called "ultrafiltration milk" has become popular on the Internet. Related manufacturers claim that it is more nutritious than ordinary milk and can drink one bottle of milk and absorb twice the nutrition. The so-called ultrafiltration milk usually refers to the milk products produced by ultrafiltration technology. As early as September 2021, this kind of milk entered the Chinese market. So, what is ultrafiltration technology? Can this technology really double the nutrition of milk? The reporter of Science and Technology Daily interviewed relevant experts to answer your questions. Like a sieve, different components of milk are separated. "Ultrafiltration technology is an industrial technology, which originated in the 1990s and belongs to membrane separation technology. According to the pore size of the membrane, membrane separation technology can be divided into four types: RO (reverse osmosis), NF (nanofiltration), UF (ultrafiltration) and MF (microfiltration)." Professor of Tianjin University of Science and Technology Yu Jinghua, a member of the expert group of the National Health Commission on the revision of dairy quality and safety standards, said in an interview with the reporter of Science and Technology Daily that the ultrafiltration membrane used in ultrafiltration technology is a membrane with a pore diameter between microfiltration and nanofiltration, and also a porous membrane with separation function, with a pore diameter of 1 to 100 nanometers. With the interception ability of ultrafiltration membrane, substances with different diameters in the solution can be separated by physical interception, so as to achieve the purpose of purification, concentration and screening of different components in the solution. Membrane technology is often used in the production and processing of various dairy products, for example, in the process of sterilization, increasing protein content, reducing lactose content, desalination, concentration, etc. "Generally speaking, ultrafiltration membrane is like a sieve, which uses sieves with different apertures to separate substances with different diameters. Relevant milk manufacturers can use ultrafiltration membrane to filter out lactose, salts and other substances with smaller molecular diameters, while retaining substances with larger protein equivalent diameters." Yu Jinghua introduced that the pore diameter of microfiltration membrane is generally larger than that of ultrafiltration membrane, The former can mainly isolate microorganisms in milk, including bacteria and spores. By using this method, the effect of disinfection and sterilization can be achieved even without high-temperature sterilization treatment. After removing part of water and lactose, the milk after ultrafiltration membrane contains more protein, calcium and less sugar than before ultrafiltration. The nutrients are concentrated, and the taste is thicker and silkier. The production standards for pure milk and fresh milk in China are GB 25190-2010 National Food Safety Standard Sterilized Milk and GB 19645-2010 National Food Safety Standard Pasteurized Milk. According to the above national standards, the minimum protein content of milk should reach 2.9g per 100ml. At present, the protein content of milk on the market is usually between 2.9 g and 3.6 g per 100 ml, but the protein content of milk after ultrafiltration process can reach 6 g per 100 ml.